296 
AMERICAN AGrRIOULTURIST, 
[August, 
The Compound Microscope—Answers to 
Questions. 
In several hundred letters recently received are numer¬ 
ous queries which are mainly answered by the following: 
The "magnifying power’' of a Simple or Compound Mi¬ 
croscope is usually stated in diameters , that is, the in¬ 
creased size shown in one direction. For example, a 
small dot (lig. 1), seen in an in¬ 
strument magnifying only 10 di¬ 
ameters, is stretched out one way 
as seen in fig. 2. But it is mag¬ 
nified in every other direction 
just as much, as shown in fig. 3. 
That is, its area or surface would 
be seen covering about 78 times 
as much space, while a small ob¬ 
ject seen through a microscope 
magnifying 100 diameters, would 
cover a space over 7,800 times as 
great as the object itself. This of course brings out many 
thousands ol points, lines, and parts, too small to be seen 
by the unaided eye. (The American Agriculturist Com¬ 
pound Microscope, by the use of single and double lenses 
and the draw-tube, can be arranged to magnify all the way 
from 25 diameters up to 150 or more, and works very clear¬ 
ly for 125 diameters, which is equivalent to magnifying 
the area or surface over 12,000 times ! 
The power and definition of this instrument is sufficient 
for all ordinary uses of amateurs and professional men. 
Those desiring higher power for special scientific inves¬ 
tigation, can be supplied with achromatic “French Trip¬ 
let" lenses, having screws to fit this instrument, and of 
almost any power desired, up to 300 or 400 diameters or 
more, at a cost of $3 to $10, according to the special 
power desired. 
This Microscope has a concave mirror, on a movable 
arm, allowing it to be turned under the stage to concen¬ 
trate light under or through transparent objects ; or at 
one side above to throw light down upon opaque objects. 
The Camera Lucida .—The long-known Camera Ob- 
scura is an arrangement for throwing an exact image of 
an object upon a screen in a dark room (obscura). The 
Camera Lucida (light) is an attachment, to the eye-piece 
of the Microscope, which throws the magnified image of 
an object upon a partially lighted screen or paper, so 
that one can see it well enough to run a pencil over it, 
and thus make a picture of the magnified object for pres¬ 
ervation. This requires only skill enough to pass a 
pencil over the picture as it shows on the paper. Until 
the production of this new Microscope, any Camera 
Lucida attachment for the Microscopes in use, alone 
cost more than this entire instrument, camera included. 
The regular retail price of the American Agriculturist 
Compound Microscope is $15,which is less than half the 
price of any equally powerful and convenient Micro¬ 
scope previously offered in this country. But it was de¬ 
vised wholly in the interest of the readers of this Jour¬ 
nal, and it is supplied to any actual subscriber for $10— 
or given as a Premium for Ten annual subscriptions at 
the regular rate of $1.50 each. 
It has received the highest commendations of many 
scientific men, as well as many hundreds of our lay 
readers. (Some of them are given in our pages for 
June, last year. Prof. Spencer F. Baird, Secretary of the 
Smithsonian Institution, at Washington, uses one, and 
has sent many persons to us to obtain them, though by 
his official position he is precluded from giving a written 
recommendation of it, as he would otherwise gladly do.) 
Other questions received are all answered, we believe, 
in the illustrated description which is sent to applicants. 
Soil Exhaustion.— Dr. J. B. Lawes gives some 
important notes on the exhaustion of soil as deduced 
from his famous field experiments. He writes: “It is 
now exactly forty years since we began to exhaust a por¬ 
tion of one of my fields by continuous unmanured wheat 
crops; it may therefore be interesting to show the evi 
dence we are in a position to bring forward upon the sub¬ 
ject of exhaustion as regards the soil at Rothamsted.... 
The annual decline due to this cause may amount from 
one-quarter to one third of a bushel of wheat per acre 
per annum. If we take the smaller quantity, and add to 
it the ordinary proportion of straw, the result would be 
equivalent to about forty pounds of produce_The a- 
mount of matter annually taken from the soil by this 
forty pounds of produce, including the nitrogen it con¬ 
tains, would be between two and three pounds. The 
evidence derived from other experiments in the same 
field, proves that the decline in produce is due to an ab¬ 
sence of nitrogen, as also that the minerals are in excess, 
but the actual amount of nitrogen that this forty pounds 
of produce would have contained, would be less than one- 
half pound in weight.” This seems like a small matter 
upon an acre of land, but it is to be observed that in for¬ 
ty years this annual decline amounts to ten bushels of 
grain. Dr. Lawes concludes that “ the gradual decline 
in the produce is due to the diminishing amount of ni¬ 
trogen in the soil. It is also evident that the source from 
which the forty crops obtained their supply must have 
been the stores of nitrogen already existing in the soil 
when the experiment commenced ; further, it seems most 
probable that the yield of future crops will depend upon 
the amount of nitrogen liberated each year from the 
soil.” It is through such long extended and carefully 
conducted experiments as these of Dr. Lawes that we are 
to learn the nature of soils, their exhaustion, etc. 
•containing a great variety of Items , including many 
good Hints and Suggestions which we throiv into smaller 
type and condensed form , for want of room elsewhere. 
Reliable Business Men, those who have 
both the ability and the intention to do what they 
promise, are the only ones invited to use the business- 
pages of this journal, and those in charge of that depart¬ 
ment are under positive instructions to admit no others 
at any price; and they try to live up to it, and generally 
do, though once in a while they may make a mistake—to 
err is human—but this seldom occurs. We could make a 
fortune in a single year, and supply the paper at lower 
rates, if the advertising pages were thrown open to those 
who gladly pay high prices, as they can afford to, 
because they give little for much. But we mean our ad¬ 
vertising pages shall be a valuable source of trustworthy 
information to our readers.—When ordering from, or cor¬ 
responding with any of our advertisers, or sending for 
catalogues, etc., it is well to state that you are a reader 
of this Journal. They will know what we expect, and 
what you expect of them as to prompt and fair treatment. 
Attending; tine Fair.— It will soon be “fair 
time,” and already preparations should be in progress 
for both attending and making exhibits at one or more 
of them. There are many reasons why the farmer and 
family should attend the fairs. It is a source of both in¬ 
struction and amusement to old and young. Many a lad 
has had his interest kindled for improved machinery, 
live stock, fruits, etc., by attending the fair. 
What is the Use ?—If “ J. B. II ,” of New Hol¬ 
land, Ohio, had signed his full name, he might long ago 
have had an answer by postal card—telling him that there 
were probably no Cashmere Goats in the country.— 
There was nothing in the question that “ J. B. H.” need 
be ashamed of; even were he candidate for President, no 
capital could be made against him. What is the use oi 
writing letters and omitting to sign them ? The general 
fate of such is the waste-paper basket. If a letter is not 
of sufficient importance for the writer to sign it, it is of 
no sort of importance to us, and three cents may be 
saved if the writer puts it into his own waste-basket. 
Brink for Hot Weather.— In England, and 
largely elsewhere, a drink is made by mixing oatmeal 
with water, three or four ounces to a gallon. It is found 
to satisfy the thirst as well, if not better, than pure water. 
The oatmeal is a nutritious food, and when taken with 
the water, while it is pleasant to the taste, the mixture 
makes a "victuals and drink” th#t is commendable. 
We like if, and have taken many a drink of it in the hay- 
field, or while hoeing the corn, etc. The Mexicans use 
upon long journeys, and herdsmen and the poorer labor¬ 
ers live upon, a food called Pinole (pronounced pin-o-lee, 
with the accent upon the o). Corn is parched, or roasted 
(not popped) and ground into meal, sufficient sugar is 
added to pleasantly sweeten it, and cinnamon or other 
spice is often used to give a pleasant flavor. In this the 
grain is thoroughly cooked, and only needs to he mixed 
with water, and one has a hearty meal ready at once. It 
is mixed with water sufficient to form a mush, or it may 
be used with a larger quantity of water, to form a gruel, 
which we know to be a most refreshing drink. 
Sorrel.—“P. R. H.,” Summit Co., O., asks how to 
exterminate Sorrel. He says that some in his vicinity 
say that it is due to “ sourness in the atmosphere.” We 
have often heard it ascribed to a sour soil, but not before 
to a “ sour atmosphere.” The best way to get rid of sor¬ 
rel is to improve the soil, and encourage the growth of 
grass to crowd it out. The idea that Sorrel, or any other 
plant, can hike up acidity from the soil is erroneous. 
Sorrel and Sugar-beet, grown side by side, will be sour 
in one case, and sweet in the other. Both the acid and 
sugar are formed in the plant, not taken up by it. 
Great Increase of Immigration.—A circu¬ 
lar issued by the Bureau of Statistics at Washington, 
shows that the number of immigrants arrived in New 
York for the year ending May 31st, 1879, was 92,351. The 
number for the year ending May 31st, 1880—236,017. 
Blossoms, but does not Bear. —Every now 
and then some one asks what can be done with a grape¬ 
vine that flowers freely, but will not bear a cluster. Ei¬ 
ther graft a good kind upon the root, or set out another 
to take its place. Some vines are imperfect in their flow¬ 
ers, and nothing will make such produce fruit. 
The American Association for the Ad¬ 
vancement of Science.—" What’s in a name ?” 
Had the poet asked with reference to this one, the cor¬ 
rect answer would have been—four dozen letters. The 
Society must have more than usual vitality, as it has car¬ 
ried that name about the country for over 28 years, and 
will hold its 29th meeting at Boston, on the 25th of the 
present month. The annual gatherings of this body of 
scientific workers are most pleasant occasions. Its mem¬ 
bers number nearly 1,000, and as those who attend are 
usually accompanied by their wives and daughters, the 
meetings are quite as social as scientific. Workers in 
every department of science get together once a year to 
tell what they have been doing. There is such a number 
that they divide up into several sections, so if one finds 
the doings in one section not to his taste, he can go to 
another. As the Association is hospitable to all listen¬ 
ers, our friends in Boston and vicinity, even if not mem¬ 
bers, will find the sessions, as a general thing, instruc¬ 
tive and enjoyable. Boston is a capital place for such a 
gathering; its people are used to entertaining crowds, 
and know how to do it.. F. W. Putnam, Salem, Mass., is 
Permanent Secretary, who will give all needed informa¬ 
tion to those intending to attend this interesting and 
instructive meeting. 
The Coming Fairs.— Our Fair-List is made up 
largely from the announcements sent us by officers of 
the Societies holding them. A large number of premium 
lists and other announcements of Fairs have already 
been received and placed on file.—To the Secretaries of 
all others we would say, please send the date and place 
at once. The State , County, and Town, as well as the 
date, should be clearly and accurately given. Also the 
Secretary’s P. O. address. 
Muck : Big it Now.— The dry weather which 
usually comes in late summer makes this a good time to 
get out a supply of muck. This valuable absorbent for 
liquid manures, when of the best quality, contains a large 
quantity of nitrogen, which, when decomposed in the 
compost heap, makes of itself a large amount of valuable 
plant food. As a source of manure, it is of importance. 
44 What is Tills ?” is a question that is, of course, 
a familiar one to us. For example, it comes to our table 
together with an object which may be described in brief 
in something like this wise. It is about two and a halt 
inches long, and half an inch in diameter, chestnut brown 
in color, round, tapering at both ends; from one end, the 
head, proceeds a long, curved proboscis, like a jug han¬ 
dle, while the opposite end is divided into a number of 
rings. It is alive, because it moves its ringed extremity 
when touched; but it is entirely helpless, for it goes 
without taking any food. This is the pupa, or chrysalis, 
of the “ Tomato Worm ” that is so destructive to the 
foliage of the tomato and several other plants. When 
the mature insect comes out of the pupa case it will be a 
large and handsome moth, of an ashen-gray color, with 
bright yellow spots on its body, and a very long tongue, 
which, when not in use, is coiled up under its head. 
“Pig in tiie Clover.”— A farm is not complete 
without pigs ; and pigs are at their best in ;a field in i 
which they have green food to pick, and a field is often 
the most profitable when it is growing a good crop of 
tender clover. The green food the pigs get acts as a cor¬ 
rective to their feed at the trough. Pigs that are getting 
clover or grass can be fed corn without the injury it would 
do them were they confined closely in pens and deprived 
of green food. When the grass is short, a feed of fodder 
corn is important, and especially so for sows that are 
rearing young pigs, as such green food increases the milk 
and keeps both sow and pigs in a healthy condition. 
